大鼠脊髓边缘细胞初级传入特点的研究

将６只Ｗｉｓｔｅｒ大鼠脊髓Ｌ（１～３）段双侧后根切断，并将ＨＲＰ注入小脑内。术后分别在２、３、４天灌杀，取出Ｌ（１～３）脊髓节段，对ＨＲＰ标记的脊髓边缘细胞及其与溃变末梢的突触联系进行了电镜观察。结果表明，在脊髓边缘细胞的胞体或近侧树突表面发现有少量的溃变终末。根据溃变终末内小泡的形状，它们属于Ｓ型和Ｆ型即球形和扁平形小泡。根据溃变终末的外形又可分为圆型和细长型。按不同术后存活期，这些终末显示的溃变特点有所不同。术后２天溃变终末主要呈电子密度增高象；术后３天溃变终末中的线粒体肿胀、溶解以及部分突触小泡溶解；术后４天的溃变终末内则表现突触小泡和线粒体大部溶解消失。各类溃变末梢周围均可见到有胶质细胞突起包绕或充填。本研究进一步证明，作为脊小脑前束起始细胞的脊髓边缘细胞所接受的外周传入从性质和特点上均与脊小脑后束的起始细胞有所不同。这些结构的不同说明脊髓边缘细胞在向小脑输送信息中有其特殊功能。

ULTRASTRUCTURAL INVESTIGATION ON PRIMARY AFFERENTS OF SPINAL BORDER CELLS OF THE RAT

Abstract The posterior rhizotomies at L1～L3and injections of HRP into the cerebellum were made in 6 rats. After 2～4 days postoperation survival time, the spinal border cells (SBC), which were located in L1～L_3of the spinal cord and labeled retrogradely by HRP, and degeneration boutons of primary afferents were examined electron-microscopically for understanding the synaptology. The results showed that a certain small number of degeneration boutons which covered the surface of cell bodies or proximal dentrites of SBC were recognized. These boutons mainly belonged to the S-or F-types which contained spherical or elliptical vesicles respectively. With regard to their shapes. these bouton could be further divided into elongated and round subtypes. There were certain morphological differences in degenerating boutons with different postoperation survival times. The degenerating boutons at 2 days postoperation survival time presented electrondense degeneration that was usually accompanied by some other changes in cell organelles. In addition, glial changes were usually presented. It was proved in the present study that the primary afferents in SBC which are the originating cells of the ventral spinocerebellar tract differ from those of the dorsal spinocerebellar tract in characters and numbers. These structural differences indicated that SBC has special functions with regard to conducting information from the spinal cord to the cerebellum.